1. Field of the Invention
The invention relates to a hold-down element for holding an electrical and/or electronic component onto a substrate, particularly for mounting a connector onto a printed circuit board, comprising a first part for engaging the substrate and a second part for engaging the substrate and a second part for engaging the component to be mounted, which first part has an essentially flat, elongated shape provided with means for engaging in a clamping manner in a mounting opening of the substrate, said means comprise a member which is raised with respect to the plane of the first part.
2. Brief Description of Prior Developments
Many different embodiments of hold-down elements of this type are know from the prior art.
European Patent Applications 0,366,964 and 0,497,554 describe hold-down element of a first type in which the first part, to be received in a mounting opening, is provided with retention hooks or retention teeth, which, in the mounted state, provide the required force for securing the respective component to the substrate by biting into the wall of the mounting opening.
Hold-down elements of this type can be used only for mounting components on substrates having such a structure that the relevant retention hooks or retention teeth can bite into it. When mounting on glass substrates, such as, for example, the substrate of a liquid crystal display device, such hold-down element cannot generally be used. For this purpose, in practice, use is made of hold-down elements of a second type which engage in a clamping manner in a mounting opening of the substrate. A hold-down element of this type is, for example, described in U.S. Pat. Nos. 3,954,242 and 5,145,405.
The hold-down element know from U.S. Pat. No. 4,538,878 is rather a combination of said first and second type.
Hold-down elements provided with retention hooks or retention teeth must be constructed in a relatively robust manner so that they can withstand the relatively powerful force required for inserting them into a mounting opening. It should also be borne in mind that these hold-down elements have to have large dimensions such that they also provide a sufficient mounting force in mounting openings whose dimensions are subject to a relatively high tolerance, for example, of the order of magnitude of 5 to 10%. Clearly, the mounting force is highest in the case of mounting a hold-down element of relatively large size in a mounting opening which, as a result of tolerance, is relatively small.
Hold-down elements which are to be mounted in a clamping manner in a mounting opening are generally constructed so as to be relatively wide, in order to provide the required fastening power, such as, for example, the hold-down element disclosed in the above mentioned U.S. Pat. No. 5,145,407.
In view of present day attempts to achieve a reduction in the scale (miniaturization) of electronic components, which, for example, include attempts at achieving connectors having a pitch distance between the contact elements of, for example, 1 mm or 1.27 mm, with the relatively thin-walled housing associated therewith, hold-down elements provided with retention hooks or retention teeth are unsuitable owing to the risk of damage to the housing resulting from the relatively high mounting forces exerted hereon during mounting.
Owing to their size, wide hold-down elements are unsuitable for being received between contact elements placed close to one another, which is the case, for example, with connectors which have to be mounted adjacent to one another without position loss ("end-to-end stackable").